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Miller" , Alexey Kuznetsov , Hideaki YOSHIFUJI , netdev , Linux MM , Cgroups , LKML Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Mar 12, 2020 at 7:03 AM Qian Cai wrote: > > On Mon, 2020-03-09 at 22:16 -0700, Shakeel Butt wrote: > > diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c > > index a4db79b1b643..65a3b2565102 100644 > > --- a/net/ipv4/inet_connection_sock.c > > +++ b/net/ipv4/inet_connection_sock.c > > @@ -482,6 +482,26 @@ struct sock *inet_csk_accept(struct sock *sk, int flags, int *err, bool kern) > > } > > spin_unlock_bh(&queue->fastopenq.lock); > > } > > + > > + if (mem_cgroup_sockets_enabled) { > > + int amt; > > + > > + /* atomically get the memory usage, set and charge the > > + * sk->sk_memcg. > > + */ > > + lock_sock(newsk); > > Here we have a deadlock, It's a missing lockdep annotation. Eric already has a patch in progress to fix this and another typo in the original patch. > > [ 362.620977][ T4106] WARNING: possible recursive locking detected > [ 362.626983][ T4106] 5.6.0-rc5-next-20200312+ #5 Tainted: G L > [ 362.633941][ T4106] -------------------------------------------- > [ 362.639944][ T4106] sshd/4106 is trying to acquire lock: > [ 362.645251][ T4106] 7bff008a2eae6330 (sk_lock-AF_INET){+.+.}, at: > inet_csk_accept+0x370/0x45c > inet_csk_accept at net/ipv4/inet_connection_sock.c:497 > [ 362.653791][ T4106] > [ 362.653791][ T4106] but task is already holding lock: > [ 362.661007][ T4106] c0ff008a2eae9430 (sk_lock-AF_INET){+.+.}, at: > inet_csk_accept+0x48/0x45c > inet_csk_accept at net/ipv4/inet_connection_sock.c:451 > [ 362.669452][ T4106] > [ 362.669452][ T4106] other info that might help us debug this: > [ 362.677364][ T4106] Possible unsafe locking scenario: > [ 362.677364][ T4106] > [ 362.684666][ T4106] CPU0 > [ 362.687801][ T4106] ---- > [ 362.690937][ T4106] lock(sk_lock-AF_INET); > [ 362.695204][ T4106] lock(sk_lock-AF_INET); > [ 362.699472][ T4106] > [ 362.699472][ T4106] *** DEADLOCK *** > [ 362.699472][ T4106] > [ 362.707469][ T4106] May be due to missing lock nesting notation > [ 362.707469][ T4106] > [ 362.715643][ T4106] 1 lock held by sshd/4106: > [ 362.719993][ T4106] #0: c0ff008a2eae9430 (sk_lock-AF_INET){+.+.}, at: > inet_csk_accept+0x48/0x45c > [ 362.728874][ T4106] > [ 362.728874][ T4106] stack backtrace: > [ 362.734622][ T4106] CPU: 22 PID: 4106 Comm: sshd Tainted: > G L 5.6.0-rc5-next-20200312+ #5 > [ 362.744096][ T4106] Hardware name: HPE Apollo > 70 /C01_APACHE_MB , BIOS L50_5.13_1.11 06/18/2019 > [ 362.754525][ T4106] Call trace: > [ 362.757667][ T4106] dump_backtrace+0x0/0x2c8 > [ 362.762022][ T4106] show_stack+0x20/0x2c > [ 362.766032][ T4106] dump_stack+0xe8/0x150 > [ 362.770128][ T4106] validate_chain+0x2f08/0x35e0 > [ 362.774830][ T4106] __lock_acquire+0x868/0xc2c > [ 362.779358][ T4106] lock_acquire+0x320/0x360 > [ 362.783715][ T4106] lock_sock_nested+0x9c/0xd8 > [ 362.788243][ T4106] inet_csk_accept+0x370/0x45c > [ 362.792861][ T4106] inet_accept+0x80/0x1cc > [ 362.797045][ T4106] __sys_accept4_file+0x1b0/0x2bc > [ 362.801921][ T4106] __arm64_sys_accept+0x74/0xc8 > [ 362.806625][ T4106] do_el0_svc+0x170/0x240 > [ 362.810807][ T4106] el0_sync_handler+0x150/0x250 > [ 362.815509][ T4106] el0_sync+0x164/0x180 > > > > + > > + /* The sk has not been accepted yet, no need to look at > > + * sk->sk_wmem_queued. > > + */ > > + amt = sk_mem_pages(newsk->sk_forward_alloc + > > + atomic_read(&sk->sk_rmem_alloc)); > > + mem_cgroup_sk_alloc(newsk); > > + if (newsk->sk_memcg && amt) > > + mem_cgroup_charge_skmem(newsk->sk_memcg, amt); > > + > > + release_sock(newsk); > > + } > > out: > > release_sock(sk); > > if (req)